NLRP3 Inflammasome Involvement in the Organ Damage and Impaired Spermatogenesis Induced by Testicular Ischemia and Reperfusion in Mice

Abstract

We investigated the role of the nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome during testis ischemia and reperfusion injury (TI/R) in wild-type (WT) and NLRP3 knock-out (KO) mice. WT and KO mice underwent 1 hour testicular ischemia followed by 4 hours and 1 and 7 days of reperfusion or a sham TI/R. Furthermore, two groups of WT mice were treated at the beginning of reperfusion and up to 7 days with two inflammasome inhibitors, BAY 11-7082 (20 mg/kg i.p.) or Brilliant Blue G (45.5 mg/kg i.p.), or vehicle. Animals were killed with a pentobarbital sodium overdose at 4 hours and 1 and 7 days, and bilateral orchidectomies were performed. Biochemical and morphologic studies were carried out in all groups. TI/R in WT mice significantly increased caspase-1 and interleukin (IL)-1b mRNA after 4 hours and IL-18 mRNA at 1 day of reperfusion (P # 0.05). There was also a significant increase in caspase-3 and terminal deoxynucleotidyl transferase-mediated digoxigenin-deoxyuridine nick-end labeling-positive cells, marked histologic damage, and altered spermatogenesis in WT mice in both testes after 1 and 7 days of reperfusion. KO TI/R mice, WT TI/R BAY 11-7082, and Brilliant Blue G treated mice showed a significant reduced IL-1b and IL-18 mRNA expression, blunted caspase-1 and -3 expression, minor histologic damages, low terminal deoxynucleotidyl transferase-mediated digoxigenindeoxyuridine nick-end labeling activity, and preserved spermatogenesis. These data suggest that the activation of NLRP3 plays a key role in TI/R, and its inhibition might represent a therapeutic target for the management of patients with unilateral testicular torsion.

Targeting the NLRP3 inflammasome to attenuate spinal cord injury in mice

“…Efficacious NLRP3 inflammasome inhibitors are currently at an early stage of research and development. One widely used compound is BAY 11-7082 [ 19 , 20 , 34 , 35 ], an I-κB kinase-β inhibitor, which selectively suppresses the ATPase activity of NLRP3 that is essential for its activation, and directly targets the NLRP3 inflammasome independently of inhibition of NF-κB activation [ 36 , 37 ]. In our studies, this compound inhibited NLRP3 inflammasome activation, reduced spinal cord tissue damage, and improved functional recovery.…”

“…Mice underwent manual bladder expression twice a day until recovery of reflex bladder emptying. The timing and dose of BAY 11-7082 [ 19 , 20 ] and A438079 [ 21 ] were based on previous studies.…”

ROS‐Mediated NLRP3 Inflammasome Activation in Brain, Heart, Kidney, and Testis Ischemia/Reperfusion Injury

“…As to the role of NLRP3 inflammasome, specific inhibitors, such as BAY 11-7082 [ 100 ] and Brilliant Blue G (BBG) [ 101 ], are able to inhibit its effects in a testicular I/R model [ 102 ]. In fact, BAY 11-7082, an I- κ B kinase- β inhibitor, and BBG, blocking the membrane-bound purinergic P2X7 receptor, showed a significant reduction of IL-1 β and IL-18 mRNA expression, blunted caspase-1 and caspase-3 expression, minor histological damage, low TUNEL activity, and preserved spermatogenesis, indicating a selectively reduced NLRP3 inflammasome activity [ 102 ]. It was also observed that NLRP3 KO mice responded to I/R insult with a lower activation of the inflammatory and apoptosis cascade than WT animals.…”

Association of Seminal Plasma Level of NLRP3 Inflammasome Protein with Quality of Seminal Fluid Parameters Among Infertile Men

“…They depend on enzymes (16) and cytokines (17) that participate in inflammatory process of male genitalia (14) . Group of researchers highlighted the importance of inflammasome protein NLRP3 as a "physiological low level of inflammation" for fertility (6).It had been suggested that low level of NLRP3 is essential for Sertoli cell production of low levels of IL1B to maintain IL1 alpha (18) but higher rate of inflammasome expression will results in higher level of inflammasome activation cytokines such as IL-1B and IL-18 (19) and served as a proinflammatory signals generating an inflammatory process in the testis such as leucocyte infiltration and cell death signaling and caspase 1 activation (20)(21)(22) .Also, it might activate ASC adaptor protein in both sperm cell and leucocytes in semen resulting in inflammatory cell death (23) . To date, the primary focus of inflammasome research has been anchored by NLRP3, which is a cytoplasmic protein that is primarily expressed in monocytes, macrophages, granulocytes, dendritic cells, epithelial cells and osteoblasts (24).…”